Fuel atomization

ABSTRACT

Fuel is continuously supplied through a nozzle to form a jet which normally remains coherent across an air-induction line and is intercepted in a collector aperture for return to the fuel system, but is during a period whose length is controlled according to fuel requirements, during each engine cycle or revolution, prevented (wholly or mainly) from reaching the collector aperture by a mechanical arrangement which destroys the alignment of the jet formed by the nozzle with the collector orifice so that the jet, with the whole or part of its crosssection, will strike an impact surface causing it to break-up into a spray which becomes mixed with combustion air. The impact surface may be struck by the jet when it is deflected, for example by an electromagnet acting through an armature on a flexible tube whose end forms the orifice, or when the collector orifice is moved out of line of the jet, or a separate baffle may be arranged to penetrate into the path of the jet without moving the orifice or the jet relative to each other.

United States Patent 11 1 Moss et a1.

[ FUEL ATOMIZATHON [75] Inventors: Norman Moss, llford; Michael John Broad, Enfield, both of England [73] Assignee: Plessey Handel und investments A.G., Zug, Switzerland [22] Filed: Jan. 13, 1972 [21] Appl. No.: 217,497

[30] Foreign Application Priority Data Jan 18, 1971 Great Britain 2,245/71 52 us. 01. 123/139 AW, 123/139 AB 717,525 10/1954 Great Britain 123/139 AW [57] I ABSACT Fuel is continuously supplied through a nozzle to form a jet which normally remains coherent across an airinduction line and is intercepted in a collector aperture for return to the fuel system, but is during a period whose length is controlled according to fuel requirements, during each engine cycle or revolution, prevented (wholly or mainly) from reaching the collector aperture by a mechanical arrangement which destroys the alignment of the jet formed by the nozzle with the collector orifice so that the jet, with the whole or part of its cross-section, will strike-an impact surface causing it to break-up into a spray which becomes mixed with combustion air. The impact surface may be struck by the jet when it is deflected, for example by an electromagnet acting through an armature on a flexible tube whose end forms the orifice, or when the collector orifice is moved out of line of the jet, or a separate baffle may be arranged to penetrate into the path of the jet without moving the orifice or the jet relative to each other.

12 Claims, 6 Drawing Figures FUEL ATOMIZATION This invention relates to the control of fuel supply to a combustion chamber and has for an object to provide an improved method and apparatus for such purposes. In British Pat. application No. 32009/69 and the corresponding U.S.A. Pat. No. 3,613,649 an arrangement is described wherein liquid fuel is supplied from a tank to a nozzle from which the fuel issues as a coherent jet arranged to normally enter, and be collected in, a collector aperture which is connected to return the fuel to the supply tank, and wherein means are provided for producing, during an adjustable part of a cycle related to the revolution of an engine to be supplied with fuel, ultrasonic vibration of the nozzle which causes the jet of fuel, as it issues from the nozzle, to break-up and fragment into a spray of droplets. During this part-period a major portion of the fuel from the nozzle by-passes the collector tube and thus reaches the combustion chamber. The present invention has for an object to provide means of achieving similar combined fuel control and fragmentation of the jet without having to rely on ultrasonic vibration of the nozzle for the fragmentation of the the jet of fuel.

According to one aspect of the invention apparatus for supplying to a mixture-burning combustion device a controlled supply of liquid fuel comprises a jetforming nozzle, means for continuously feeding to said nozzle a liquid fuel under pressure to normally form a solid jet of liquid fuel passing across a chamber or passage containing a combustion-sustaining gas into a collector aperture so arranged as to intercept such solid jet and conduct the fuel in it out of said chamber or passage, and meansoperable to so interfere with the normal flow from said nozzle as to break-up and prevent at least some of the liquid forming the solid jet from entering the collector aperture. The measns operable to interfere with the normal flow of the jet may be operated periodically for a time variable in accordance with the fuel requirements of the combustion device. For

this purpose deflecting-means may be provided which are operable to cause all, or a preferably adjustable part, of the fuel in the jet to impact on a surface and fragment into a spray of droplets, thereby preventing during such operation removal by the collector aperture of the fuel, or of such part of the fuel, issuing from the nozzle.

The deflecting means may be arranged to deflect the nozzle and thereby the jet out of alignment with the collector aperture. Alternatively the deflecting means may be arranged to deflect the collector aperture out of alignment with the nozzle. In either case the surface on which the jet impacts may be an end surface of a collector tube forming the aperture, or it may be a surface extending from such collector aperture, while a further possibility is the use of a baffle to act as an impact surface separate from the element containing the collector aperture, in which case the deflecting means may be arranged to control penetration of this baffle into the cross-section of the jet without affecting the mutual alignment of the nozzle and the collector aperture. In each case the impact surface may be at an angle other than normal to the direction of flow of the jet from the nozzle, thereby causing a spray of droplets to be directed in a particular direction and if required to form a spray of a particular shape, e.g., a fan-shaped spray.

The means of deflecting either the nozzle, element containing the collector aperture, or the baffle may be an electromagnet attracting or repelling the element in question, or two electromagnets, arranged on opposite sides of the element to be moved, in order to move the element in both directions, control being effected by varying the degree of deflection and/or the ratio of the time in which the fuel is, due to such deflection, atomised by reaching the impact surface to the time in which there is no deflection and in which therefore substantially all the fuel in the jet is removed through the collector tube. If desired, the deflection may be effected by subjecting the nozzle at spaced time intervals to vibratory movements which may be of a high or ultrasonic frequency to cause the jet, during the time of such operation, to be periodically deflected and impact on the said surface.

In the application of the invention to a reciprocating combustion engine or other device requiring a periodic supply of a fuel-and-air mixture the nozzle and the collector aperture may be inserted in the air inlet duct to the engine and the jet arranged to strike an impact surface during each induction cycle for a period dependent on the momentary fuel requirements of the engine. The movement of the nozzle, baffle, or collector aperture may be in the form of a discrete pulse, in which case the length of the pulse in conjunction with the flow rate of fuel in the jet and the amplitude of the movement will determine the quantity of fuel reaching the engine at each pulse. Alternatively pulses of oscillation of a frequency high compared to the pulse frequency may be applied to the tube or nozzle or baffle in a direction transverse to that of the jet. The quantity of fuel reaching the engine or other consumer is determined by the duration of each pulse of oscillations and the pulse frequency. The frequency of the oscillations is not critical and may be in the infrasonic, sonic or ultrasonic range.

Five embodiments of the invention will now be described with reference to the accompanying drawing, in which FIG. 1 is an elevational diagram showing an arrangement including a fixed nozzle and a movable collector tube,

FIGS. 2 and 3 similarly show respectively two arrangements each including a movable nozzle and a fixed collector tube,

FIG. 4 similarly shows an arrangement in which a nozzle is oscillated,

FIG. 5 shows a modified arrangement having a fixed nozzle and a fixed collector tube, in conjunction with a movable baffle, and

FIG. 6 shows a detail of an arrangement similar to that of FIG. l but having a modified impact surface.

Referring now first to FIG. 1, a fuel-supply tank 1 is connected by a line 2 to a fuel pump 3, which pressu-- rises the fuel and supplies it through a delivery line 4 to the nozzle 5 which is so shaped as to normally provide a coherent jet 7 of fuel. A collector tube 6 constitutes the shorter one of two straight parallel tubular portions joined by a semicircular tubular portion to form a collector structure 8, and its bore is arranged to be normally aligned with the jet of fuel issuing from the nozzle 5, so that normally all, or substantially all, the fuel issuing from the nozzle will enter the inlet aperture or collector orifice 9 of the collector tube 6 and pass through the tube structure 8 and a fuel-return line 10 to be returned to't he inlet of the pump 3, to be recycled through the system. To supply fuel from the jet 7 at a metered rate to a combustion device and incidentally to cause the fuel thus supplied to be broken-up into a spray of droplets, the structure 8 is mounted resiliently, or made resilient itself to permit movement of its inlet aperture 9 transversely to the jet 4, and an electromagnet 11 is arranged to co-operate with a magnetic armature 12 secured to the longer leg of the tube structure 8 to move, when the electromagnet is energised, the collector aperture 9 at the free end of the collector tube 6 transversely out of alignment with the jet 7 so that at least a portion of the cross-section of the jet 7 will impinge on an impact surface 90 provided on the end portion of the collector tube and will be broken-up by the impact into a spray of droplets.

In the illustrated embodiment the nozzle and the inlet 9 end of the collector tube 6 are arranged in-such manner in the induction line 50 of a combustion engine 51, which may be a reciprocating-piston engine, that when the electromagnet 1 I is de-energised, the solid jet 7 extends across the flow of air in the induction line 50 to reach the inlet aperture 9 of the collector tube 6, and

. substantially no fuel will be conveyed to the engine by the induced air flow in the line 50. When, however, the electromagnet I1 is energised to attract its armature 12, the resulting movement of the armature will displace the collector structure from the position shown in full lines at 8 to the position shown in broken lines at 8', thereby displacing the inlet aperture of the collector tube 6 fromthe full-line position 9 in alignment with the jet 7 to the brokenline position 9', which is laterally to the right, in the Figure, of the jet 7. The jet will therefore no longer reach the collector tube. At the same time the impact surface will move from the fullline position 9a laterally of the jet 7 into the position shown in broken lines at 9a; which is in the line of the jet 7. The jet 7 will therefore impinge on the surface 9a, the jet will be broken-up by the impact, and the resulting small particles of the liquid fuel will be reflected by the impact surface to form a spray cone, indicated at 57, which extends across the air flow in the induction line 50, and due to the large surface-to-volume ratio of the small particles, the fuel will be suspended in the air in droplet form and will thus be conveyed to the engine.

In the embodiment illustrated in FIG. 2 a nozzle which, similarly to nozzle 5 of FIG. 1, forms the fuel supplied by a pump 3 into a coherent jet 22 normally aligned with a fixed collector tube 21, is flexibly mounted at 23 so that it may be pivotally moved to a position in which the jet 22 passes laterally of the inlet aperture of the collector tube 21. To effect this movement of the nozzle 20 an electromagnet 24 is arranged to act upon an armature 25 secured to the nozzle 20. On energisation of the electromagnet 4 the coherentjet 22 of fuel is deflected out of alignment with the collector aperture of the tube 21 so as to impinge on an impact surface 21g which is attached to the inlet end of the collector tube 21 laterally of its orifice, and the impact will break-up the jet of fuel similarly to the action of the impact surface 9a in the embodiment described with reference to FIG. 1. An adjustable stop 52 limiting the approach of the armature 25 to the magnet 24 is provided to permit adjustment of the part of the crosssection of the jet in which, when the magnet is energised, the fuel of the jet will impact on the surface 21 to be fragmented into a spray of droplets which are carried away by the flow of combustion air in the passage 50 and thus prevented from being removed by the colleetor orifice.

In the arrangement shown in FIG. 3, a nozzle 30 forms the fuel supplied by the pump 3 into a coherent jet 34, which is normally aligned with a collector tube 35. This nozzle extends at right angles from a resiliently flexible tube 32, so that flexure of the tube 32 will result in angular deflection of the jet 31 without substantial transverse movement of the nozzle 30 itself. An electromagnet 33 acting in the direction of the jet 31 of fuel on a magnetic armature 34 secured to the tube 32 is provided to deflect the tube and thus alter the direction of the jet 34 while the centre of the nozzle 30 remains substantially on the lineof the axis of the collector tube 35. This alteration of the direction of the jet 34 will cause the jet to strike an impact surface 350 provided at the end of the collector tube 35 laterally of the inlet aperture of the collector tube with a result similar to that produced upon the jet 7 in the embodiment of FIG. l by the impact on the surface 9a.

In the embodiment illustrated in FIG. 4 a nozzle 40 forms the fuel supplied by the pump 3 into a coherent jet 42 normally aligned with a collector tube 41, and a piezoelectric vibrator 43 is arranged when energised to vibratorily move the nozzle 40 perpendicularly to its axis, thus causing the jet 42 to move in periodic fashion into and out of alignment with the inlet aperture of a fixed collector tube 41. Provided that the frequency of the vibrator is high in relation to the length of each period or pulse of energisation of the vibrator, this will cause, during each period of energisation, a predetermined portion of the fuel supplied by the jet to miss the collector inlet orifice and be broken-up by impact to be carried with the combustion air along the induction line, while the remaining portion of the fuel forming the jet 42 will reach the collector inlet orifice and will thus be returned to the inlet side of the pump 3. If desired, the vibrator frequency may be as high as to be in the ultrasonic range.

FIG. 5, in which the same references as in FIG. I have been used to designate corresponding items, both the nozzle 5 and the collector inlet aperture 9 are fixed in mutually aligned positions, the aperture 9 being formed in a wall 15. In order to prevent for desired periods the jet 7, or part of its cross-section, from reach- .ing the aperture 9 and cause it to be scattered into the combustion air, a baffle element 13, separate from the member 15 containing the collector orifice 9, is prpvided and arranged to be movable into and out of engagement with the coherent jet 7. To effect such movement, the baffle 13 is connected to the armature 12 of the electromagnet I1 and a spring assembly 14 is arranged to urge the baffle 13 to a position clear of the jet, while the electromagnet is so arranged that when it is energised, its armature will move the baffle 13 against the spring action into the line of the jet 7.

The invention is not limited to the details of the embodiments described hereinabove. Thus if required in any one of the embodiments the movement-of the nozzle, tube or the impact surface may alternatively be effected by two electromagnets respectively operative to move the elements into and out of alignment with each other. Furthermore, by varying the shape, the inclination, and/or the surface finish of the baffle or of the impact surface at the inlet end of the collector tube, the spray of fuel after impingement of thejet can be varied in its shape and its direction, and a suitable built-up lug or the like may be formed on the collector tube close to its inlet end to provide the impact surface for the jet. Such an arrangement is illustrated in FIG. 6, in which the impact surface is provided on a lug 9b built-up at one side of the collector tube 9, which latter is shown in the position g1 which it assumes when the electromagnet shown at 11 in F 16. 1 is energised. This impact surface is so shaped and disposed that the spray cone 57b produced by the impact of the jet 7 upon the surface is inclined to the axis of the jet at a larger angle than in the case of FIG. 1, and also has a desired shape, being for example, fan-shaped.

On the other hand, whilst the invention is suitable for many types of combustion equipment, for example for furnaces and for gas turbines, it is believed to offer particular advantages when used in conjunction with displacement-type internal-combustion engines. In that case the nozzle and collector tube may, as illustrated in FIG. 1 be mounted in the air induction passage leading to the combustion chamber or chambers of the engine so that the fuel may be mixed with the combustion air before it enters the combustion chamber, and the frequency and the length of the periods in which during each induction stroke or each revolution of the engine, the jet is wholly or partly prevented from reaching the collector aperture, may be automatically controlled in response to the fuel requirements of the engine, for example by a control system somewhat similar to that described in the complete specification of British Pat. No. 1,138,536.

What we claim is:

1. Apparatus for supplying controlled amounts of liquid fuel to a mixture-burning combustion device, which comprises a passage member having a passage for conveying combustion air to the combustion device, a jetforming fuel-nozzle member having a nozzle arranged to discharge a solid jet of fuel into said passage, means for continuously feeding to said nozzle liquid fuel under pressure, a fuel-collector member having a collector orifice in said passage and forming a line leading from said orifice to a point outside said passage, said collector orifice being normally so aligned with said nozzle as to intercept the whole of said solid jet of fuel, an impact member having an impact surface approximately facing said nozzle but normally displaced laterally from the line of said solid jet so as to be clear of said jet, and control means operable for moving at least one of said members to so alter the relative alignment of said members as to cause at least part of the cross-section of said solid jet to strike said impact surface thereby causing the fuel conveyed in said part of the cross-section to be scattered by the impact and deflected in atomized form into the flow of combustion air in said passage.

2. Apparatus as claimed in claim 1, which includes automatic means which cause the said control means to be operated periodically for a time variable in accordance with the fuel requirements of the combustion device.

3. Apparatus as claimed in claim 2, wherein said control means include an electromagnet for producing the movement of at least one of said members.

4. Apparatus as claimed in claim 2, which further includes a reciprocatory combustion engine having an operating cycle that includes an induction stroke, said passage being connected to said engine for supplying fuel-and-air mixture to the engine, and said automatic means being arranged to operate said control means during each induction stroke of the engine for a period of a length dependent on the momentary fuel requirements of the engine.

5. Apparatus as claimed in claim 1, wherein the collector member and the impact member are fixed in relation to said passage member, said control means being operable to move the nozzle member transversely to the direction of the jet from its normal position of alignment of the nozzle with the collector orifice to a position in which at least part of the cross-section of the jet will strike the impact surface instead of entering the collector orifice.

6. Apparatus as claimed in claim 1, wherein said nozzle member is fixed in relation to said passage, said control means being operable to move the collector member transversely to the direction of the jet to a position in which part of the cross-section of the jet will pass outside the collector orifice so as to strike the impact surface.

7. Apparatus as claimed in claim 6, wherein said impact member is fixed to said collector member, with the impact surface extending from the collector member laterally of the collectororifice.

8. Apparatus as claimed in claim 1, wherein the nozzle member and the collector member are fixed in relation to the passage member with the nozzle and collector orifice in mutual alignment, the control means being operable to move the impact member transversely to the direction of the jet from a position in which the impact surface is positioned laterally adjacent to and clear of the jet at a point between said nozzle and said orifice, to a position in which the impact surface extends across at least part of the cross-section of the jet.

9. Apparatus as claimed in claim 1, wherein said control means are adjustable to vary the portion of the cross-section of the jet that strikes the impact surface.

10. Apparatus as claimed in claim 1, wherein the disposition of the impact surface to a surface normal to the jet is such as to render the reflected spray asymmetrical relative to the axis of the jet, or non-circular in cross-section.

11. Apparatus as claimed in claim 1, wherein said control means include transducer means operable to produce when energised vibratory movement of one of said members transversely to the direction of said solid jet.

12. Apparatus as claimed in claim 1, wherein said control means include transducer means operable to produce when energised vibratory movement of said nozzle member transversely to. the direction of said 

1. Apparatus for supplying controlled amounts of liquid fuel to a mixture-burning combustion device, which comprises a passage member having a passage for conveying combustion air to the combustion device, a jet-forming fuel-nozzle member having a nozzle arranged to discharge a solid jet of fuel into said passage, means for continuously feeding to said nozzle liquid fuel under pressure, a fuel-collector member having a collector orifice in said passage and forming a line leading from said orifice to a point outside said passage, said collector orifice being normally so aligned with said nozzle as to intercept the whole of said solid jet of fuel, an impact member having an impact surface approximately facing said nozzle but normally displaced laterally from the line of said solid jet so as to be clear of said jet, and control means operable for moving at least one of said members to so alter the relative alignment of said members as to cause at least part of the cross-section of said solid jet to strike said impact surface thereby causing the fuel conveyed in said part of the cross-section to be scattered by the impact and deflected in atomized form into the flow of combustion air in said passage.
 2. Apparatus as claimed in claim 1, which includes automatic means which cause the said control means to be operated periodically for a time variable in accordance with the fuel requirements of the combustion device.
 3. Apparatus as claimed in claim 2, wherein said control means include an electromagnet for producing the movement of at least one of said members.
 4. Apparatus as claimed in claim 2, which further includes a reciprocatory combustion engine having an operating cycle that includes an induction stroke, said passage being connected to said engine for supplying fuel-and-air mixture to the engine, and said automatic means being arranged to operate said control means during each induction stroke of the engine for a period of a length dependent on the momentary fuel requirements of the engine.
 5. Apparatus as claimed in claim 1, wherein the collector member and the impact member are fixed in relation to said passage member, said control means being operable to move the nozzle member transversely to the direction of the jet from its normal position of alignment of the nozzle with the collector orifice to a position in which at least part of the cross-section of the jet will strike the impact surface instead of entering the collector oriFice.
 6. Apparatus as claimed in claim 1, wherein said nozzle member is fixed in relation to said passage, said control means being operable to move the collector member transversely to the direction of the jet to a position in which part of the cross-section of the jet will pass outside the collector orifice so as to strike the impact surface.
 7. Apparatus as claimed in claim 6, wherein said impact member is fixed to said collector member, with the impact surface extending from the collector member laterally of the collector orifice.
 8. Apparatus as claimed in claim 1, wherein the nozzle member and the collector member are fixed in relation to the passage member with the nozzle and collector orifice in mutual alignment, the control means being operable to move the impact member transversely to the direction of the jet from a position in which the impact surface is positioned laterally adjacent to and clear of the jet at a point between said nozzle and said orifice, to a position in which the impact surface extends across at least part of the cross-section of the jet.
 9. Apparatus as claimed in claim 1, wherein said control means are adjustable to vary the portion of the cross-section of the jet that strikes the impact surface.
 10. Apparatus as claimed in claim 1, wherein the disposition of the impact surface to a surface normal to the jet is such as to render the reflected spray asymmetrical relative to the axis of the jet, or non-circular in cross-section.
 11. Apparatus as claimed in claim 1, wherein said control means include transducer means operable to produce when energised vibratory movement of one of said members transversely to the direction of said solid jet.
 12. Apparatus as claimed in claim 1, wherein said control means include transducer means operable to produce when energised vibratory movement of said nozzle member transversely to the direction of said solid jet. 